Hello Chris and Welcome to JA,
You will most likely end up removing the cover/pan to inspect the harness that goes to all the solonoids and then to inspect the valvebody and the TCC solonoid itself. If you have a multimeter then you could ohm through the harness and even the solonoid. I have found that most of the time this code was produced because of the solonoid itself. But it could be the circuits to it also. There is abig connector an top of the trans that goes into the trans and the internal harness ispect that connector for any corrosion or damaged pins or wires. Good Luck and if you need more just ask please.